SunBall replies

[gregwatson]

Hi All,

I'm the inventor and developer of the SunBall.

A few points:

1. The current ex tax price of the SunBall is USD$1,100. By the US intro in 3rd qtr 2006 I expect the price to be <$1,000.
   
2. With Adelaide solar availability the SunBall will generate 660kWhs annually. The SunBall calculator page has a graphic for the US that you can use to calculate your solar availability.
   
3. $/kWh is then $1,000 / 25 years life / 660 kWhs annually = $0.06 / kWh. I suggest if you compare what flatties can produce kWhs for will find the SunBalls $0.06 / kWh is much lower.
   
4. The cells don't burn up cause they are mounted on a massive heat sink and only get about 10 - 15 deg C above ambient. Typical flattie NOCT (Normal Operating Cell Temperature) is 27 deg C above ambient. So if anything is going to burn up it is flatties.
   
5. The cells I use derate thermally at -0.04% conversion loss / deg C as against flatties at -0.55% conversion loss / deg C. Thats 13.7 times lower thermal effect.
   
6. Combining the low thermal cell efficiency loss with the massive heat sink with true dawn to dusk tracking gives exceptional hot summer afternoon electricity generation, totally overlapping network loading.
   
   

I posted this here cause the board didn't allow me to comment on the existing topic.

All the best,

Greg Watson

Green and Gold Energy

Adelaide, South Australia

+61 408 843 089

http://www.greenandgoldenergy.com.au

Online SunBall discussion group

http://groups.yahoo.com/group/sunball

[Clifford]

Thanks for the info...

I would be curious about a cost comparison between the "Sunball" vs a similar "traditional" solar panel.

As I understand it, the important thing is the surface area exposed to the sun.  Reading through the literature on the sunball, it is a large lense that takes it's "surface area" and focuses it into a smaller area of the "cells".

I guess the other issue is mounting.  

A "traditional" panel mounts easily on a roof.  It might be awkward to mount one or more sunballs on the roof.

Someone commented earlier about the durability of the lense.

I have two vehicles...  one a 1967 Fiat...  Headlight lenses (glass) are crystal clear.

The 91 Ford, however, has plastic lenses.  I would hate to imagine the loss of transparency...  (is the sunball subject to similar issues?)

Replaceable parts?  If one wished to replace / upgrade the solar cells in 10 yrs, are there a half a dozen quarter sized cells that could easily be upgraded?

Anyway, it looks like unique technology, and I would certainly be interested if the price was right (someone mentioned a "bulk discount").

[gregwatson]

Thanks for the info...

I would be curious about a cost comparison between the "Sunball" vs a similar "traditional" solar panel.

* To do that properly you need to compare flat panel $/kWh output to SunBall $/kWh. The SunBalls rated 330W output is what it produces where as flat panels loose 30% at 40 deg C, the SunBall only loses about 2%. So when the suns really shines the SunBall toughs it out and delivers the kWhs to spin your meter backward. Then the dawn to dusk tracking picks up over 50% more solar energy. Basically flatties produce annual kWhs at about 1,200x their peak rating and the SunBall produces annual kWhs at about 2,000 its peak rating.

As I understand it, the important thing is the surface area exposed to the sun.  Reading through the literature on the sunball, it is a large lense that takes it's "surface area" and focuses it into a smaller area of the "cells".

* The collection of the light onto a space cell designed to handle the energy density is only part of the solution. The triple junction cell then converts everything from about 300nm (UV), through the visible portion of the spectrum, and well into the far IR (1,800nm)

http://www.greenandgoldenergy.com.au/images/SpectrolabCellSpectrum.jpg

* The result is a record setting current best efficiency of 39.6%. The cells used in the SunBall are rated at 35% @ 500 suns concentration. Here is a picture of the Spectrolab test bed in the heat of the Arizona desert. The black stick looking things pointing up from the cells are tha passive heat radiators:

http://www.greenandgoldenergy.com.au/images/SpectrolabPassive.jpg

I guess the other issue is mounting.  

A "traditional" panel mounts easily on a roof.  It might be awkward to mount one or more sunballs on the roof.

* Each SunBall is easily mounted on the roof, directly over a rafter. Two metal straps wrap the rafter and hold the SunBall to the roof.

Someone commented earlier about the durability of the lense.

I have two vehicles...  one a 1967 Fiat...  Headlight lenses (glass) are crystal clear.

The 91 Ford, however, has plastic lenses.  I would hate to imagine the loss of transparency...  (is the sunball subject to similar issues?)

* The material used in the lens is optical acrylic and absorbs less than 2% of the UV, passing most of it to the UV hungery upper cell layer. It UV stabilized and does not discolour. The lenses are bounded to the inside of the outer 3mm toughtened glass lens protector. The lenses are not exposed to the outside enviroment. I suspect your 91 Ford lens suffered from abrasion from road impact dust and dirt as you drove along. Thats why the outer surface of the lens assembly is a sheet of 3mm toughtened glass.

Replaceable parts?  If one wished to replace / upgrade the solar cells in 10 yrs, are there a half a dozen quarter sized cells that could easily be upgraded?

* This is where the SunBall shines. Everything is replaceable, lens assembly, cells, motors, electronics, etc. The motors are brushless sealed gearheads with a run life of 20,000+ hours. 25 years of service in the SunBall will see maybe 100 - 200 hours of motor use. The lens assembly is designed and tested to withstand hail stone impacts to the same standard as flat panels. As part of the testing procedure the whole SunBall unit is heat soaked for 1,000 hours (~42 days) at 85 deg C and 85% humidity. ALL the electronics, cells, wiring interconnects, motors, etc must be sealed to withstand and survive this test.

Anyway, it looks like unique technology, and I would certainly be interested if the price was right (someone mentioned a "bulk discount").

* It is very unique product. Thanks for the kind comments.

* I would be interested in such a bulk purchase idea. I can ship partly dissassembled (but fully tested) SunBalls at about 450 / 40ft container so shipping charges are very small. Reassembly takes about 20 - 30 minutes and requires only normal hand tools and skills.

** Maybe someone would be willing to act as a distributor for the group, do the reassembly and internal US shipping for a small charge?

All the best,

Greg Watson

Green and Gold Energy

Adelaide, South Australia

+61 408 843 089

http://www.greenandgoldenergy.com.au

Online SunBall discussion group

http://groups.yahoo.com/group/sunball

[veewee77]

I have a question. . .

Your website states that the motors in your tracking assembly are brushless DC motors.

In the photo of the tracking unit, however, they are, however, little brush-type DC motors commonly found in toy cars and etc. Were these just prototype motors for that photo, or are those the actual motors used in the units?

The direct link to that specific photo is:

http://www.greenandgoldenergy.com.au/images/P9200002.jpg

Thanks

Doug

[gregwatson]

Hi Doug,

You have a sharp eye. Yes the motors in the 0.4m prototype are brush types with external gear boxes. I did this so I could adjust the gear ratios if needed. The motors in the 1m2 unit are sealed brushless gearheads as stated.

All the best,

Greg Watson

Green and Gold Energy

Adelaide, South Australia

+61 408 843 089

http://www.greenandgoldenergy.com.au

Online SunBall discussion group

http://groups.yahoo.com/group/sunball

[pyrocasto]

"* I would be interested in such a bulk purchase idea. I can ship partly dissassembled (but fully tested) SunBalls at about 450 / 40ft container so shipping charges are very small. Reassembly takes about 20 - 30 minutes and requires only normal hand tools and skills.

** Maybe someone would be willing to act as a distributor for the group, do the reassembly and internal US shipping for a small charge?"

I'm sure there are quite a few of us here, including me, that would be willing to do the distributor thing for everyone. The only problem is the $250k-500k 240 units would cost. I'm kinda doubtful that anyone has that kind of money upfront, or the patience to get rid of that many(since I doubt unfortunantly this group would buy all 240 units).

Too bad your located in Aus. Makes shipping a little more expensive.

I hope this doesnt sound bad, do you have an apx price for a bulk buy like that? If you do and dont want to post it publically shoot me an email.

Thanks

[pyrocasto]

Ahh, the 240 in my post should have been 450. Not sure how I got that figure off. :s

[finnsawyer]

At $.06 per kwh I'll take a pass on this because of the time and risks involved, not to mention the cost of the grid tie for net metering.  Get it down to $.03 and increase the size to produce 500 kwrs per month in the summer and I'm interested.  You claim a 25 year life.  Do you guarantee it for that time?  You have created a more complicated system than regular solar panels, which means more can go wrong.  So, it's less likely one would get to the 25 year life time without a failure.  What happens when the unit sits with a foot of snow over it, or gets encased in ice?  Does the gear head then strip?  America has extremely varied weather.  When I was at my daughter's north of Austin, Texas last Xmas they had snow south of there.  Of course Florida has Hurricanes.  If you're going to sell them here, you need to design for the conditions.  I live at 47 degrees north latitude and we get 250 inches of snow a year.  At this point you basically have a toy.  Increase the collecting diameter by a factor of three and you will have an energy generating machine.  If you wish to penetrate the American market, you might do well to involve an establish engineering or manufacturing firm.  Of course, if you'd like to send me a demonstration unit I would be happy to test it.  It's snowing right now with up to eight inches predicted with blizzard conditions for tonight and tomorrow.  Cheers.

[gregwatson]

At $.06 per kwh I'll take a pass on this because of the time and risks involved, not to mention the cost of the grid tie for net metering.  Get it down to $.03 and increase the size to produce 500 kwrs per month in the summer and I'm interested.

* 10 SunBalls can generate 6,600kWhs annually or 550kWhs per month. $0.03 will happen but not in 2006.

You claim a 25 year life.  Do you guarantee it for that time?  You have created a more complicated system than regular solar panels, which means more can go wrong.  So, it's less likely one would get to the 25 year life time without a failure.  

* All SunBall components have a prorated 25 year guarantee. Know of any flat panels which offer that?

* The SunBall is a solar appliance and as such it can be repaired. Individual cells can be replaced, likewise the tempered glass / optical acrylic lens assembly can be replaced. With flatties any internal failure / glass crack and the whole panel is replaced as tey can't be repaired. I know of no level of engineering which can deliver fault free service for 25 years. So like all good engineers I selected the parts for many more than 25 years of service life and if something does fail, it can be simply and easily replaced. Lens assembly, cells, wiring, motors, electronics, etc. The onboard micro has an event log which helps to diagnose failures and a wireless connection back to our server (assuming there is mobile phone coverage).

What happens when the unit sits with a foot of snow over it, or gets encased in ice?  Does the gear head then strip?  

* The motor drive current is monitored by the onboard micro. The motors will not drive to self destruction. Instead if the hemisphere can't move the SunBall will wait for the problem to be resolved. The motors are driven by a graduated PWM technique so a stuck hemisphere is easy to detect even at a low drive level. Additionally the final hemisphere 2 axis drive is not by gears. It is also not frictional.

America has extremely varied weather.  When I was at my daughter's north of Austin, Texas last Xmas they had snow south of there.  Of course Florida has Hurricanes.  If you're going to sell them here, you need to design for the conditions.  I live at 47 degrees north latitude and we get 250 inches of snow a year.  

* The SunBall will be certified to the same exacting requirements as flat panels. IEC61215. You can't get that certification unless it's tough. Really tough. They fire ice balls at it, roast it at 85 deg C and 85% humidity for 1,000 hours (~42 days). Then freeze it, spray it with salt water, put simulated snowloads on the top, try to fry it with high voltage discharges and generally try to destroy it.

At this point you basically have a toy.  

* With respect what I have decided to share are photos of a old prototype. You expect me to totally lay on the table all the details of the 1m2 production unit? Like maybe it's made from carbon fibre and not aluminium?

Increase the collecting diameter by a factor of three and you will have an energy generating machine.  

* The 1.1m diameter unit is about as big as you would want to go to put on a roof. I take it you are referring to the 0.4m prototype?

If you wish to penetrate the American market, you might do well to involve an establish engineering or manufacturing firm.  

* The SunBall will be manufactured in a totally specialized manufacturing facility to world standard best practice. Only way to fly.

Of course, if you'd like to send me a demonstration unit I would be happy to test it.  It's snowing right now with up to eight inches predicted with blizzard conditions for tonight and tomorrow.  Cheers.

* It's early summer here in Adelaide. Maybe I'll come over with my skis?

GeoM

* Greg

[BigBreaker]

I think you are being a bit harsh on the cost and technology, but do bring up some good points.

In my part of the US electricity is over 20 cent/kWh on the meter so your cost breakeven is certainly not the only one.

The extra mechanics and higher wind profile for the sunball is a concern.  I'd need some convincing before using 25 yr amort period.  I'd also like to see wind tunnel tests, etc... to assure durability.  For larger purchases I think they should include some replacement tracker units.

Anyone living in CA with those high $/kWh charges should really consider these.  With a proper roof design they could be make invisible to neighbors and make great use of insolation in a limited area.

PS Flat plates have trouble with ice and snow as well....

[MountainMan]

Greg,

An interesting invention.  I'm not sold on the all important step of "invention-->production ready product".  For one thing, what sort of life testing have you done on your mechanism for moving the cells around inside the ball?  It is one thing to say that the motors will last forever, but what about the foam wheels?  Are we sure they won't wear out in a year or get cross-linked by the high solar intensity and cease to have enough friction with the inside of the ball to move the stuff around?  What is in your design to keep dust and dirt out of the ball so as not to degrade the traction of the tracking mechanism.

One other point I would make that is purely business and not technical.  I believe you are doing yourself a disservice by showing early prototypes on your site with pictures taken in your back yard.  Now that you are moving into production, you would do well to divorce yourself from the "back yard inventor" mystique and work to provide a much more corporate appearance for your company.

And finally, the base for your ball is too obviously an upside down steel bowl.  You need to do something to make it less apparent that you stole a bowl from your wife's kitchen and smashed in the bottom of it to make the base for your "product".

I think what you are doing is cool.  Everything I've mentioned here is an effort to steer you in a more profitable and successful direction rather than any attempt to put down your efforts to date.

I hope you have much success with this venture.

best,

jp

[gregwatson]

The extra mechanics and higher wind profile for the sunball is a concern.  I'd need some convincing before using 25 yr amort period.  I'd also like to see wind tunnel tests, etc... to assure durability.  For larger purchases I think they should include some replacement tracker units.

* We will do wind loadings as required for all Australian wind zones including cyclone conditions. The rafter attachment method I use is very strong. The max wind handling has more to do with how the rafter / trust has been designed. Prelim data suggests 1 SunBall per rafter should handle upto that which the roof can handle. It's actually quite slippery due to the round lens assembly and hemispherical back side. I'm looking at putting in a stress sensor for high wind load areas providing real time feedback to the micro which can actively rotate the SunBall vertically searching for the best angle of attact to the wind to produce the lowest stress on the roof.

Anyone living in CA with those high $/kWh charges should really consider these.  With a proper roof design they could be make invisible to neighbors and make great use of insolation in a limited area.

* Totally agree.

PS Flat plates have trouble with ice and snow as well....

** I'm eager to see what some smarts in the micro software can do to handle snow and ice.

All the best,

Greg Watson

Green and Gold Energy

Adelaide, South Australia

+61 408 843 089

http://www.greenandgoldenergy.com.au

Online SunBall discussion group

http://groups.yahoo.com/group/sunball

[gregwatson]

Greg,

An interesting invention.  I'm not sold on the all important step of "invention-->production ready product".  

* I'm a professional product development engineer who preaches "design for manufacturing" as an integerated process.

For one thing, what sort of life testing have you done on your mechanism for moving the cells around inside the ball?  

* Moving the cells generates no stress on them. They are bounded to a aluminium heat spreader.

It is one thing to say that the motors will last forever, but what about the foam wheels?  

* What is what I used for the prototype. The 1m2 production unit uses a stainless steel drive system. Nothing to wear out there.

Are we sure they won't wear out in a year or get cross-linked by the high solar intensity and cease to have enough friction with the inside of the ball to move the stuff around?  What is in your design to keep dust and dirt out of the ball so as not to degrade the traction of the tracking mechanism.

* The Hemisphere is totally sealed. It will float in water.

One other point I would make that is purely business and not technical.  I believe you are doing yourself a disservice by showing early prototypes on your site with pictures taken in your back yard.  

* I show reality. No flash spin doctoring here. You are all invited along to see it happen on the internet. Very open stuff.

Now that you are moving into production, you would do well to divorce yourself from the "back yard inventor" mystique and work to provide a much more corporate appearance for your company.

* In the end it's about being open and honest with my customers. What's wrong with doing business with a real human face and not some corporate board room generated image. Not my way. By the way two backyard inventors totally changed the world when they invented the airplane.

And finally, the base for your ball is too obviously an upside down steel bowl.  You need to do something to make it less apparent that you stole a bowl from your wife's kitchen and smashed in the bottom of it to make the base for your "product".

* It's actually an upside down dogs bowl so I dodn't need to do much modification. The hemishpere is a dome light. Nice existing stainless steel products that I didn't need to pay for tooling charges. Again it's a actual working prototype that I take all over the place to demo. It's very different to the production test units I'm building now.

I think what you are doing is cool.  Everything I've mentioned here is an effort to steer you in a more profitable and successful direction rather than any attempt to put down your efforts to date.

* I do understand that. Just understand my company is about developing and selling a product people want and need and not about doing some smoke and mirrors spin doctor dance. Your feedback goes straight into the development of the final production units.

I hope you have much success with this venture.

** I will. Come along for the ride, make comments and watch it all happen thanks to the magic of the internet. Together we will change forever the way we humans generate electricity on this planet.

best,

jp

MountainMan, Julian California

http://www.real-home-based-business-opportunity.com

My ultimate hobby project is to build a ten foot tall robot.

[finnsawyer]

Thanks for the info.  I think I should mention that in this area we are required to design our trusses for an eighty pound per square foot snow load.  It's not the snow per say, but that fact that you can have two feet of packed snow on the roof followed by a hard rain.  The snow acts like a sponge with the obvious result.  I don't think I would mount a Sun Ball on a roof around here.  Question:  Does the sun ball unit automatically follow the sun's motion through the year, and what is it's range.  During the summer here the sun rises in the north east and sets in the north west and daylight can be 16 hours long.  While I may agree about your unit being the maximum size I'd put on a roof, I'd be willing to build a dedicated structure for a larger unit, as I'm sure many others would be.  Some free engineering advice:  Take seven of the collecting units and mount them to one drive motor.  You should be able to market this larger unit at a considerable cost savings per kwh.  It will also increase your potential market (you sell seven collecting units at a time).  You can also build and sell the support structures.

 There's a ski hill called Mount Bohemia north of here.  Beautiful views of Lake Superior (when it's not snowing).  Not a beginner's slope.

[finnsawyer]

Around here electricity cost around 9 cents per kwh.  That's what I was basing my comments on.  I'm sure these units would have a market for remote sites not needing much electricity, but I also believe larger units would be desirable.  I gave him my ideas in another comment.  If I had a larger unit I would probably mount it in some sort of a green house due to the winters we get around here.  He seems like a decent chap.

[richhagen]

I'm not sold on your product yet, but I am always happy to see people thinking about problems and trying to solve them.  I am getting to have quite a few of the "flatties" as you call them, and note that some of the old Arco panels and maybe some of the Siemens panels I have are probably at or over 25 years old (thats only 1980 after all) and still going strong  (I bought most of the really old ones second hand).  While I rewired a few that I had not done a proper job of connecting to start, added combiner boxes, rewired for a change in system voltage, and had problems with amorphous type panels, the monocrystaline and polycrystaline panels have never given me problems from the units themselves.  By virtue of its design, your system is more complex, so for it to be worth it to me, the cost per watt, about $4/peak watt for the "flatties" with my installation labor, has to be less to make up for the additional maintenance issues of the tracking system.  If they were the same, why would I deal with the hassles of increased maintenance?  For me, I am in an urban environment, with mostly pre-existing buildings with flat roofs.  The additional wind loading would be an issue that I would have to consider, not just out of concern for your unit, but a hundred year old roof rafter might not be up to the task of handling the additional load in a 70MPH gust.  If they do make it over here I might try to pick one up just to compare and "play" with.  I suspect that if the efficiency is there, your major maket will be larger installations with larger arrays of units.  I appreciate your taking the time to post and reply on it here.  I will be watching with interest to see if you have truly overcome the lense and heat problems of earlier concentrator type designs, as well as the robustness of the tracker.  Rich Hagen  

[gregwatson]

I'm not sold on your product yet, but I am always happy to see people thinking about problems and trying to solve them.  

* Just stick around. You will be convinced.

I am getting to have quite a few of the "flatties" as you call them, and note that some of the old Arco panels and maybe some of the Siemens panels I have are probably at or over 25 years old (thats only 1980 after all) and still going strong  (I bought most of the really old ones second hand).  While I rewired a few that I had not done a proper job of connecting to start, added combiner boxes, rewired for a change in system voltage, and had problems with amorphous type panels, the monocrystaline and polycrystaline panels have never given me problems from the units themselves.  

* Yes I totally agree. Flatties are very reliable. Partly because of the test conditions imposed by IEC61215. Here is a breakdown of what the SunBall will need to pass with flying colours:

* http://www.greenandgoldenergy.com.au/Documents/IEC_61215_61646_en.pdf

By virtue of its design, your system is more complex, so for it to be worth it to me, the cost per watt, about $4/peak watt for the "flatties" with my installation labor, has to be less to make up for the additional maintenance issues of the tracking system.  If they were the same, why would I deal with the hassles of increased maintenance?  

* You need to breakaway from just looking at $/W and look at the real cost of $/kWh. There is no maintenance on the tracking system. Every morning the SunBall finds the sun and tracks it using a combination of predicted and real time sky point update.

* Unless there is a major, major drop in flattie $/W the only way to get a lower $/kWh is to use high efficiency cells, with concentration to reduce the number of cells and tracking. So if you do the numbers on the relative $/kWh between the two technologies the choice is very simple. Stay with flatties and their very much higher $/kWh or move to the SunBall with it's moving parts and a much lower $/kWh.

For me, I am in an urban environment, with mostly pre-existing buildings with flat roofs.  The additional wind loading would be an issue that I would have to consider, not just out of concern for your unit, but a hundred year old roof rafter might not be up to the task of handling the additional load in a 70MPH gust.  

* The wind load on a 1m2 circular surface with a hemispherical backside is not as much as you would suspect. Also the torque / twist point is only about 100mm (4") off the roof. I'm going for a cyclone wind load rating at 150kph (well above 70mph) where the SunBall loading is only a very small part of the entire roof loading

If they do make it over here I might try to pick one up just to compare and "play" with.  I suspect that if the efficiency is there, your major maket will be larger installations with larger arrays of units.  I appreciate your taking the time to post and reply on it here.  

* I appreciate your time and thoughtful questions.

I will be watching with interest to see if you have truly overcome the lense and heat problems of earlier concentrator type designs, as well as the robustness of the tracker.  

* There are at least 12 Fresnel concentrator using passive heat dissipation I know of: http://www.greenandgoldenergy.com.au/othertrackers.htm

* Using the hemisphere gives the SunBall 1.8:1 the heat dissipation area versus solar collection area ratio. All other passive designs have been limited to a 1:1 ratio. This helps to really cool the cells. Also the hemisphere shape of the heat radiator surface is much more efficient in trapping cooling breezes than a flat box shape. Just this added design element totaly transforms the ability to dissipate heat. Then add in the high conversion efficiency where 35% of the solar energy exits as cool electricity. The end effect is a heat load per cm2 of 0.03W/cm2 versus 0.09W/cm2 of flatties. Further factor in the conversion efficiency loss of -0.04%/deg C versus silicon at -0.55%/deg C and you start to see the SunBall is totally off the planet in reard to heat management and the effect on conversion efficiency loss.

* As far as I know only Amonix has passed a hail stone impact test. The SunBall goes the extra mile in using a toughtened 3mm low iron glass outer panel to achieve a very high hail stone impact resistance AND protect the softer optical acrylic lens material AND provide additional extreme temperature structural support. I know of no other concentrator which has addressed and fixed the three biggies of Fresnel lenses:

1. hail stone impact resistance
   
2. long term weathering of the outer optical surface
   
3. thermal sagging at extreme temperatures
   
   

Again the SunBall has gone where no other tracking concentrator has gone. It has been designed as a true Solar Appliance which will provide 25+ years of service on your roof.

Rich Hagen  

** Greg

[antw]

I have tried for the past few days to see your website, but it just times out.  Is New Zealand blocked from seeing it, or maybe it is my internet provider?

Can any other Kiwis see his website?

Regards

Antony

[gregwatson]

I have tried for the past few days to see your website, but it just times out.  Is New Zealand blocked from seeing it, or maybe it is my internet provider?

Can any other Kiwis see his website?

Regards

Antony

Hi Anthony,

Probably just very busy. Site downloads are running very high due to the New Inventors presentation clip I put up.

Best regards,

Greg

[DanG]

Just pondering a flock of R2D2 solar collectors roosting along roof ridge lines...

- and wondered about acid rain effects. Drizzle and light showers are most acidic here in Minnesota, so even morning & evening dew cycles condensate etches on any and all susceptible surfaces during cold weather.

I own two pairs of levi denim jeans each with one knee burned through from where I knelt down to make an adjustment on my truck a couple of days in a row during a drizzly weekend. After setting in the hamper untill washday, the cloth that had been dampened on the asphalt driveway disappeared during the wash-dry cycles - also maybe why it's best to live upwind from major cities during heating season!!!

[gregwatson]

Just pondering a flock of R2D2 solar collectors roosting along roof ridge lines...

* Interesting image. I like it!

- and wondered about acid rain effects. Drizzle and light showers are most acidic here in Minnesota, so even morning & evening dew cycles condensate etches on any and all susceptible surfaces during cold weather.

* The SunBall outer surface is made of the same stuff flat panels are made from. Toughtened glass and aluminium. The SunBall's aluminium is anodized. This should help to reduce any acid etching effects on the hemisphere.

** As the SunBall lens assembly spends most of the time vertical (overnight waiting for the rising sun) there would be much less corrosive effects on the lens assembly than a fixed flat panel. Then factor in the SunBall warms up as soon as the sun rises and in so doing dries up any dew on the outer surfaces. Got to add you can replace the SunBall lens assembly at very much less cost than replacing an acid washed flat panel.

All the best,

Greg Watson

Green and Gold Energy

Adelaide, South Australia

+61 408 843 089

http://www.greenandgoldenergy.com.au

Online SunBall discussion group

http://groups.yahoo.com/group/sunball